krb5 commit: Simply OpenSSL PKCS7 decryption code
Greg Hudson
ghudson at mit.edu
Fri May 10 11:06:10 EDT 2019
https://github.com/krb5/krb5/commit/210356653a2f963ffe9a8a1b1627c64fb8ca7a3d
commit 210356653a2f963ffe9a8a1b1627c64fb8ca7a3d
Author: Robbie Harwood <rharwood at redhat.com>
Date: Mon May 6 13:13:06 2019 -0400
Simply OpenSSL PKCS7 decryption code
Fold pkcs7_decrypt() and pkcs7_dataDecode() into a single function,
and make it output the plaintext rather than a BIO.
[ghudson at mit.edu: continued a modernization of pkcs7_dataDecode() into
a larger refactoring]
src/plugins/preauth/pkinit/pkinit_crypto_openssl.c | 211 ++++++--------------
1 files changed, 62 insertions(+), 149 deletions(-)
diff --git a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
index 5ff81d8..8aa2c52 100644
--- a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
+++ b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
@@ -81,12 +81,8 @@ static int openssl_callback (int, X509_STORE_CTX *);
static int openssl_callback_ignore_crls (int, X509_STORE_CTX *);
static int pkcs7_decrypt
-(krb5_context context, pkinit_identity_crypto_context id_cryptoctx,
- PKCS7 *p7, BIO *bio);
-
-static BIO * pkcs7_dataDecode
-(krb5_context context, pkinit_identity_crypto_context id_cryptoctx,
- PKCS7 *p7);
+(krb5_context context, pkinit_identity_crypto_context id_cryptoctx, PKCS7 *p7,
+ unsigned char **data_out, unsigned int *len_out);
static ASN1_OBJECT * pkinit_pkcs7type2oid
(pkinit_plg_crypto_context plg_cryptoctx, int pkcs7_type);
@@ -1964,9 +1960,6 @@ cms_envelopeddata_verify(krb5_context context,
{
krb5_error_code retval = KRB5KDC_ERR_PREAUTH_FAILED;
PKCS7 *p7 = NULL;
- BIO *out = NULL;
- int i = 0;
- unsigned int size = 0;
const unsigned char *p = enveloped_data;
unsigned int tmp_buf_len = 0, tmp_buf2_len = 0, vfy_buf_len = 0;
unsigned char *tmp_buf = NULL, *tmp_buf2 = NULL, *vfy_buf = NULL;
@@ -1991,26 +1984,13 @@ cms_envelopeddata_verify(krb5_context context,
}
/* decrypt received PKCS7 message */
- out = BIO_new(BIO_s_mem());
- if (pkcs7_decrypt(context, id_cryptoctx, p7, out)) {
+ if (pkcs7_decrypt(context, id_cryptoctx, p7, &tmp_buf, &tmp_buf_len)) {
pkiDebug("PKCS7 decryption successful\n");
} else {
retval = oerr(context, 0, _("Failed to decrypt PKCS7 message"));
goto cleanup;
}
- /* transfer the decoded PKCS7 SignedData message into a separate buffer */
- for (;;) {
- if ((tmp_buf = realloc(tmp_buf, size + 1024 * 10)) == NULL)
- goto cleanup;
- i = BIO_read(out, &(tmp_buf[size]), 1024 * 10);
- if (i <= 0)
- break;
- else
- size += i;
- }
- tmp_buf_len = size;
-
#ifdef DEBUG_ASN1
print_buffer_bin(tmp_buf, tmp_buf_len, "/tmp/client_enc_keypack");
#endif
@@ -2072,8 +2052,6 @@ cleanup:
if (p7 != NULL)
PKCS7_free(p7);
- if (out != NULL)
- BIO_free(out);
free(tmp_buf);
free(tmp_buf2);
@@ -5714,39 +5692,6 @@ cleanup:
return retval;
}
-static int
-pkcs7_decrypt(krb5_context context,
- pkinit_identity_crypto_context id_cryptoctx,
- PKCS7 *p7,
- BIO *data)
-{
- BIO *tmpmem = NULL;
- int retval = 0, i = 0;
- char buf[4096];
-
- if(p7 == NULL)
- return 0;
-
- if(!PKCS7_type_is_enveloped(p7)) {
- pkiDebug("wrong pkcs7 content type\n");
- return 0;
- }
-
- if(!(tmpmem = pkcs7_dataDecode(context, id_cryptoctx, p7))) {
- pkiDebug("unable to decrypt pkcs7 object\n");
- return 0;
- }
-
- for(;;) {
- i = BIO_read(tmpmem, buf, sizeof(buf));
- if (i <= 0) break;
- BIO_write(data, buf, i);
- BIO_free_all(tmpmem);
- return 1;
- }
- return retval;
-}
-
krb5_error_code
pkinit_process_td_trusted_certifiers(
krb5_context context,
@@ -5827,118 +5772,86 @@ cleanup:
return retval;
}
-static BIO *
-pkcs7_dataDecode(krb5_context context,
- pkinit_identity_crypto_context id_cryptoctx,
- PKCS7 *p7)
+/* Originally based on OpenSSL's PKCS7_dataDecode(), now modified to remove the
+ * use of BIO objects and to fit the PKINIT internal interfaces. */
+static int
+pkcs7_decrypt(krb5_context context,
+ pkinit_identity_crypto_context id_cryptoctx, PKCS7 *p7,
+ unsigned char **data_out, unsigned int *len_out)
{
- unsigned int eklen=0, tkeylen=0;
- BIO *out=NULL,*etmp=NULL,*bio=NULL;
- unsigned char *ek=NULL, *tkey=NULL;
- ASN1_OCTET_STRING *data_body=NULL;
- const EVP_CIPHER *evp_cipher=NULL;
- EVP_CIPHER_CTX *evp_ctx=NULL;
- X509_ALGOR *enc_alg=NULL;
- STACK_OF(PKCS7_RECIP_INFO) *rsk=NULL;
- PKCS7_RECIP_INFO *ri=NULL;
-
- p7->state=PKCS7_S_HEADER;
-
- rsk=p7->d.enveloped->recipientinfo;
- enc_alg=p7->d.enveloped->enc_data->algorithm;
- data_body=p7->d.enveloped->enc_data->enc_data;
- evp_cipher=EVP_get_cipherbyobj(enc_alg->algorithm);
- if (evp_cipher == NULL) {
- PKCS7err(PKCS7_F_PKCS7_DATADECODE,PKCS7_R_UNSUPPORTED_CIPHER_TYPE);
- goto cleanup;
- }
+ krb5_error_code ret;
+ int ok = 0, plaintext_len = 0, final_len;
+ unsigned int keylen = 0, eklen = 0, blocksize;
+ unsigned char *ek = NULL, *tkey = NULL, *plaintext = NULL, *use_key;
+ ASN1_OCTET_STRING *data_body = p7->d.enveloped->enc_data->enc_data;
+ const EVP_CIPHER *evp_cipher;
+ EVP_CIPHER_CTX *evp_ctx = NULL;
+ X509_ALGOR *enc_alg = p7->d.enveloped->enc_data->algorithm;
+ STACK_OF(PKCS7_RECIP_INFO) *rsk = p7->d.enveloped->recipientinfo;
+ PKCS7_RECIP_INFO *ri = NULL;
- if ((etmp=BIO_new(BIO_f_cipher())) == NULL) {
- PKCS7err(PKCS7_F_PKCS7_DATADECODE,ERR_R_BIO_LIB);
- goto cleanup;
- }
+ *data_out = NULL;
+ *len_out = 0;
- /* It was encrypted, we need to decrypt the secret key
- * with the private key */
+ p7->state = PKCS7_S_HEADER;
/* RFC 4556 section 3.2.3.2 requires that there be exactly one
* recipientInfo. */
if (sk_PKCS7_RECIP_INFO_num(rsk) != 1) {
pkiDebug("invalid number of EnvelopedData RecipientInfos\n");
- goto cleanup;
+ return 0;
}
-
ri = sk_PKCS7_RECIP_INFO_value(rsk, 0);
- (void)pkinit_decode_data(context, id_cryptoctx,
- ASN1_STRING_get0_data(ri->enc_key),
- ASN1_STRING_length(ri->enc_key), &ek, &eklen);
- evp_ctx=NULL;
- BIO_get_cipher_ctx(etmp,&evp_ctx);
- if (EVP_CipherInit_ex(evp_ctx,evp_cipher,NULL,NULL,NULL,0) <= 0)
+ evp_cipher = EVP_get_cipherbyobj(enc_alg->algorithm);
+ if (evp_cipher == NULL)
+ goto cleanup;
+ keylen = EVP_CIPHER_key_length(evp_cipher);
+ blocksize = EVP_CIPHER_block_size(evp_cipher);
+
+ evp_ctx = EVP_CIPHER_CTX_new();
+ if (evp_ctx == NULL)
goto cleanup;
- if (EVP_CIPHER_asn1_to_param(evp_ctx,enc_alg->parameter) < 0)
+ if (!EVP_DecryptInit(evp_ctx, evp_cipher, NULL, NULL) ||
+ EVP_CIPHER_asn1_to_param(evp_ctx, enc_alg->parameter) <= 0)
goto cleanup;
/* Generate a random symmetric key to avoid exposing timing data if RSA
* decryption fails the padding check. */
- tkeylen = EVP_CIPHER_CTX_key_length(evp_ctx);
- tkey = OPENSSL_malloc(tkeylen);
- if (tkey == NULL)
+ tkey = malloc(keylen);
+ if (tkey == NULL || !EVP_CIPHER_CTX_rand_key(evp_ctx, tkey))
goto cleanup;
- if (EVP_CIPHER_CTX_rand_key(evp_ctx, tkey) <= 0)
- goto cleanup;
- if (ek == NULL) {
- ek = tkey;
- eklen = tkeylen;
- tkey = NULL;
- }
- if (eklen != (unsigned)EVP_CIPHER_CTX_key_length(evp_ctx)) {
- /* Some S/MIME clients don't use the same key
- * and effective key length. The key length is
- * determined by the size of the decrypted RSA key.
- */
- if (!EVP_CIPHER_CTX_set_key_length(evp_ctx, (int)eklen)) {
- ek = tkey;
- eklen = tkeylen;
- tkey = NULL;
- }
- }
- if (EVP_CipherInit_ex(evp_ctx,NULL,NULL,ek,NULL,0) <= 0)
- goto cleanup;
+ /* Decrypt the secret key with the private key. */
+ ret = pkinit_decode_data(context, id_cryptoctx,
+ ASN1_STRING_get0_data(ri->enc_key),
+ ASN1_STRING_length(ri->enc_key), &ek, &eklen);
+ use_key = (ret || eklen != keylen) ? tkey : ek;
- if (out == NULL)
- out=etmp;
- else
- BIO_push(out,etmp);
- etmp=NULL;
+ /* Allocate a plaintext buffer and decrypt data_body into it. */
+ plaintext = malloc(data_body->length + blocksize);
+ if (plaintext == NULL)
+ goto cleanup;
+ if (!EVP_DecryptInit(evp_ctx, NULL, use_key, NULL))
+ goto cleanup;
+ if (!EVP_DecryptUpdate(evp_ctx, plaintext, &plaintext_len,
+ data_body->data, data_body->length))
+ goto cleanup;
+ if (!EVP_DecryptFinal(evp_ctx, plaintext + plaintext_len, &final_len))
+ goto cleanup;
+ plaintext_len += final_len;
- if (data_body->length > 0)
- bio = BIO_new_mem_buf(data_body->data, data_body->length);
- else {
- bio=BIO_new(BIO_s_mem());
- BIO_set_mem_eof_return(bio,0);
- }
- BIO_push(out,bio);
- bio=NULL;
+ *len_out = plaintext_len;
+ *data_out = plaintext;
+ plaintext = NULL;
+ ok = 1;
- if (0) {
- cleanup:
- if (out != NULL) BIO_free_all(out);
- if (etmp != NULL) BIO_free_all(etmp);
- if (bio != NULL) BIO_free_all(bio);
- out=NULL;
- }
- if (ek != NULL) {
- OPENSSL_cleanse(ek, eklen);
- OPENSSL_free(ek);
- }
- if (tkey != NULL) {
- OPENSSL_cleanse(tkey, tkeylen);
- OPENSSL_free(tkey);
- }
- return(out);
+cleanup:
+ EVP_CIPHER_CTX_free(evp_ctx);
+ zapfree(plaintext, plaintext_len);
+ zapfree(ek, eklen);
+ zapfree(tkey, keylen);
+ return ok;
}
#ifdef DEBUG_DH
More information about the cvs-krb5
mailing list